The xanthoside composition of the crude extract of Umbilicaria proboscidea (L.) Schrader was characterized using LC-UV diode array detection and LC-atmospheric pressure chemical ionization (APCI) MS methods. The presence of acylated xanthone-O-glucosides was determined by both positive and negative ion LC-APCI-MS methods. Based on UV and MS spectral data and NMR spectroscopy, a total of 14 compounds (6-O-acylated umbilicaxanthosides A and B) were identified in U. proboscidea for the first time. In order to further develop the applicability of LC-MS techniques in phytochemical characterization, the effect of different ionization energy on fragmentation was studied using APCI. The optimal ionization conditions were achieved in positive ion APCI by using ammonium acetate buffer and in negative ion APCI by using formic acid (pH 4).
glycosides, Umbilicaria proboscidea, plant materials, acylated xanthone glycosides
NCBI PubMed ID: 12800927Publication DOI: 10.1016/s0021-9673(03)00501-6Journal NLM ID: 9318488Publisher: Amsterdam; New York: Elsevier
Correspondence: Rezanka T
Institutions: Institute of Microbiology, Prague, Czech Republic, Department of Pharmaceutical Chemistry and Natural Products School of Pharmacy, Hebrew University of Jerusalem, Jerusalem, Israel
Methods: 13C NMR, 1H NMR, gel filtration, NMR-2D, GC-MS, acid hydrolysis, HPLC, extraction, LC/APCI-MS
Found